Clutch



1945- L. E. LA BRIE 2,374,688

CLUTCH Filed Feb. 20, 1941 4 Sheets-Sheet 1 INVENTOR I r l E lager 27145172..

wmwmr-M 1 ATTORN EYS I May 1, 1945- L E. LA BRIE CLUTCH Filed Feb. 20, 1941 4 Sheets-Sheet 2 INVENTOR I jzzafger Z, XaZrze.

i 1945- L. E. LA BRIE 2,374,688

CLUTCH Fi led Feb. 20, 1941 4 Sheets-Sheet 3 I f 7; l

INVENTOR TTORN 5Y5.

y L E. LA BRIE 2,374,688

CJLUTCH Filed Feb. 20, 1941 V 4' Sheets-Sheet 4 [Ill/1 INVENTOR jflaigrz dzrld.

ATTORNEY-5- Patented May 1, 1945 UNITED STATES PATENT OFFICE CLUTCH Application February 20, 1941, Serial No. 379,786 I 10 'Claims.

This invention relate to clutches in general and in particular to clutches of the servo type.

The principal object of my invention is to provide a servo clutch which is more compact, easier to operate and smoother in operation than those of the prior art.

An additional object is to provide a clutch of this type which is readily adapted for manual or power operation.

A further object is to provide simple and effective means for initiating operation of the servo mechanism for controlling engagement of the clutch.

A still further object is to provide novel and efficient power actuating mechanism for clutches of this general type.

A still further object is to provide an expanding spring type clutch wherein torque may be transmitted in either direction, thus making possible use of clutches of this type in installations where overrunning or free-wheeling of one shaft or structure relative to the other is not desired.

Further objects and advantages will become apparent from the following description of preferred embodiments of the invention, reference being made to the accompanying drawings in which:

Fig. 1 is a longitudinal elevational view, partly in section, of an embodiment of the clutch adapted for manual operation.

Fig. 2 is a view of the clutch expansion spring and actuating lug as viewed along the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary view of the parts shown in Fig. 2 as seen when looking in the direction of the arrow 3.

Fig. 4 is a sectional view taken along line 4-4 of Fig. l.

Fig. 5 is a fragmentary sectional view along line 5-5 of Fig. 1.

Fig. 6 is a fragmentary view of the Fig. 1 clutch adapted for differential fluid pressure operation.

Figs. 7. 8 and 9 are similar views showing the clutch adapted for operation respectively by magnetic means, by a solenoid and by electrical eddy current means.

Fig. 10 is a fragmentary sectional view along the line l0l0 of Fig. 9.

Fig. 11 is a longitudinal elevational view, partly in section, of a further modification, and

Fig. 12 is a-sectional view along line l2-l2 of Fig. 11.

Referring now to Figs. i -5, inclusive, my improved clutch is illustrated in a typical environment forming a releasable driving connection between a driving shaft 10 and a driven shaft H. The former is preferably adapted to be driven by a prime mover and the latter connected to a load, such as for example, the input shaft of a motor vehicle transmission. It is, however, obvious that my improved clutch is not necessarily restricted in use to the specific relationship shown.

. Splined on the driving shaft ID at I2 is the clutch driving element l3, which for convenience of manufacture is made up of two parts It and I5 riveted together at l6. Aretaining nut l'l threadedly engages the hollowed-out end portion of the shaft H1 at 18 and serves to retain'the clutch element l3 against displacement. The driven shaft II is reduced in size at one end and i piloted in the hollow end of shaft I0, an antifriction bearing rotatably separating. the two.

The driven element of the clutch comprises the structure 20, which for convenience of manufacture is made up. of the parts 2| and 22 riveted together at 23. The element 20 is splined on the shaft ll at 24. The portion 22 thereof carries the clutch engaging element which consists of a coil spring 25 staked at one end thereof 25A (Fig. 2) to the driven portion 22 by pins 26 and 21. The spring 25 is formed of spring material of substantially rectangular cross-section and is wound such that it is adapted to normally closely. engage the outer cylindrical surface 28 of the portion 22 of the driven element 20. The opposite end 253 (Fig. 2) of the spring is adapted for engagement by a lug 29 which is riveted at 30 to the clutch pilot member 3|. A pin 250 (Fig. 2) retains the spring 25 endwise on the portion 22 of the driven element and may also serve as a stop for the lug 29 of the pilot clutch member when the spring is released.

The pilot member 3| is of dished annular construction and is journaled on the driven shaft I I at 32. A piece of friction'material 33 is secured to the inner cylindrical surface of the member 3| and the parts are designed to be assembled in such relation that the friction material 33, which has a conically shaped inner surface, is adapted to telescope the rearwardly extending portion of the driving element 13 as illustrated in Fig. 1. The latter is formed with a conical clutch surface 34 with which the friction material 33 is adapted to engage.

The member 3i is urged by a coil spring 35 in such position that the friction material 33 en-. gages the clutch surface 34 and under such circumstances, clockwise rotation of shaft ID will cause corresponding rotation of pilot member 3|. This will. in turn, cause the lug 29 to exert pressure on the rear end 253 of spring 25 tending to unwind the spring. Unwinding of the spring 25 will be accompanied by increase in diameter thereof and the outer surface of the spring will engage the inner cylindrical surface 36' of the driving element portion l5 thereby establishing a torque transmitting connection between the elements l3 and 20.

The spring 35 reacts against one race of an anti-friction ball bearing 36, preferably of the sealed type, which is prevented from displacement; alon shaft H by snap ring 31. i

It is of course apparent that, as so far described, the clutch will transmit torque in one direction only. This is necessarily true because, if the driving thrust is shifted from shaft ID to shaft H (as would occur upon coasting of the vehicle in a motor vehicle installation) the spring 25 will tend to wind up under inherent tension, there no longer being thrust imposed thereon by lug 29, and thus will disengage from the surface 36.

In order to prevent overrunning of the shaft H relatively to the shaft l9 and to providertwoway torque transmission through the clutch, a reverse type roller clutch device is operatively disposed between the elements |3 and 20. This roller clutch device comprises a set of overrunning rollers 38 which are retained in spaced relation by a cage 39, a spring 40 being provided for urging the cage toward driving position as is conventional in these types ofclutch devices. The outer surface of the member 2| is provided with a set of cams 4| in the vicinity of the rollers and these cams are so shaped that the rollers will wedge between the higher portions of the cams and the inner cylindrical surface of the member I4 whenever the member 2| tends to rotate faster than the member 4.

The pilot member 3| may be disengaged from the driving member |3 by a release mechanism which includes an anti-friction release bearing 42. The inner race 43 thereof is staked to the pilot member 3| by snap rings 45 and the outer race of the bearing has a driven fit with the inner cylindrical surface of a release collar 46. The latter has a shoulder 49 adapted for engagement by the depending ends 41 of a release yoke 48 which is keyed at 50 to a shaft 5|. The shaft 5| is adapted to, be operated by any suitably constructed manually actuated mechanism such as a pedal or a hand operated linkage,

The operation of the clutch will be readily understood from the above description, it being apparent that the spring 35 will act to engage the friction shoe 33 with the conical surface 34 of the driving structure, whereupon the pilot member 3| will rotate in the direction of the driving structure and the lug 29 will unwind the clutch spring 25 carried by the driven structure which will frictionally engage the surface 36 of the driving structure and thereby establish a driving connection between the two structures. Rotation of the shaft 5| in a counterclockwise direction will disengage the friction shoe and conical surface thus permitting release of the said driving connection because the spring 25 will immediately contract due to its inherent drive will be transmitted through the rollers 38 which will wedge between the members l4 and 2|. By properly adjusting the clearance between the rollers 38 and the cams 4| with relation to the slight rotation required to fully engage the spring 25 with the member I5, it is possible to reduce the blacklash upon torque reversal to an extremely small amount which is practically unnoticeable. When the pilot member 3| is disengaged, the driving shaft I0 is free to overrun the driven shaft I, but the driven shaft II is prevented at all times from overrunning the driving shaft 0.

With the parts illustrated, it is possible to transmit approximately fifty times more torque through the friction connection established 'by the spring 25 than through the friction connection between the shoe 33 and the surface 34. Any other mechanical advantage derived may of course be obtained by varying the sizes and adjustment of the parts.

My improved clutch is particularly well adapted for power control and I have illustrated several different applications thereof.

Fig. 6 illustrates the clutch of Fig. 1 adapted for fluid pressure control. The pilot member 3| in this form of the invention is formed with an overhanging annular portion 52 which forms tension in response to a'release of pressure at a fluid pressure cylinder adapted'for reciprocation along the shaft against the spring 35*;

a, bearing 36 accommodating relative rotation between the pilot member and the spring. A stationary piston 53 surrounds the shaft II and has a chamber 54 which communicates with a source of pressure fluid through a pipe 55. The chamber 54 is connected by a passage 56 with the chamber 51 of the cylinder 52. A snap ring 58 prevents rearward axial movement of the piston 53 and suitable rings 59, 60 and 6| are provided to insure a fluid-tight assembly. By providing a suitable valve for controlling admission of pressure fluid to chamber 54 the engagement of the pilot member 3| with the clutch driving element 3 may be controlled.

Fig. 7 illustrates the Fig. 1 clutch adapted for magnetic control. In this modification the portion I5 of the clutch driving element I3 is formed with a rear annular portion 62 which carries a field coil 63, the latter being connected by a wire 64 with a collector ring 65. The ring 65 is carried by an insulating ring 68 carried by the member l5 A carbon brush 66, carried by an insulating plug 61, is connected by means of a wire 69 with a source of electrical potential, the return being effected through the metal of the assembly, which is intended to be grounded in accordance with conventional motor vehicle practice. The brush 66 is mounted on a stationary part of the assembly 10 through the intermediary of a threaded plug 1| which is provided with a bore for receiving the insulating fitting 61 and a spring 12 which is adapted to urge the brush 66 into contact with the collector ring 65. The clearance between members l5 and 3| is slight (in the order of eight to-ten thousandths) and a friction ring I3 of asbestos fibre or other suitable clutch facing material is carried by the annular portion 62 as shown.

Upon energization of the field coil 63, the pilot member 3| will be attracted by the magnetic flux flowing around the magnetic circuit surrounding the coil and will move axially against the force of the spring 35 into contact with the member I5 A snap ring 14 limits the movement of the pilot 3| under the force of the spring 35 to the limit of the desired clearance.

In the form of the invention illustrated in Fig.

8, an electrical solenoid, generally designated at 15, controls the action of the pilot member 3|. The solenoid includes a field coil 16 carried by an irOn field structure 11 which is mounted on a stationary part 18 of the assembly. The pilot 3| has a rearwardly extending sleeve portion 19 which is reduced to receive an annular iron core 80, the latter being held against displacement on the aforesaid reduced portion by a ring 8|.

The coil 16 is grounded to the metal structure at one end and the other end is adapted to be connected by a wire 82 with a source of electrical energy, a suitable contact structure 83 being provided. Inasmuch as the coil 16 is stationary, no brush or slip ring is necessary.

The pilot 3| is normally urged axially against the ring 84 by the spring 35, and upon energization of the solenoid field coil 16 moves axially toward the left of Fig. 8 to engage the friction shoe 33 of the pilot clutch.

In this modification, the pilot 3| and the ring 18' which separates the field structure from the part 18 are preferably made of stainless steel which is of extremely high reluctance, thereby confining the fiux path to the iron of the solenoid.

Figs. 9 and illustrate the Fig. l clutch adapted for eddy-current control. In this form of the device, the stationary partof the assembly 84' carries an annular iron field structure 85.

The latter is U-shaped in cross section and carries a field coil 86 adapted for. energization through a wire 81 connected to one end thereof, the other end of the coil beinggrounded. A stainless steel separator ring 88 is interposed between the field structure 85 and the portion 84' and for best results, the 'driving member l5 and the outer periphery of an iron ring 93 carried by the pilot member 3| as illustrated. The pilot member has an integral lug 29 for actuating the spring 25 and is fixed against axial displacement on the driven shaft H by washer 94 and snap ring 95.

Energization of field coil 86 will cause magnetic flux to flow through the field structure 85 and across the air gap between the bifurcated portions thereof. The reluctance of the air gap will of course be lowered by the presence of the iron of the members 89 and 93, and because of the juxtapositioned teeth on these members there will be alternate regions of high and low flux density: the flux being high in the regions of the teeth and low in the regions between the teeth. Upon rotation of the driving member 89 therefore, a point on the latter moves alternately through regions of high and low flux density, thus the flux flowing through said point varies in magnitude and eddy currents are induced in the members 89 and 93. These eddy currents flow in a direction perpendicular to the path of the flux and range in voltage in accordance with the speed of the driving member 89. They induce a are adapted to alignflux and tends to prevent relative rotation between the members 89 and 93. This is in accordance with Lenzs law which states, in effect, that change in magnitude of a magnetic field induces a current so directed that its magnetic eiIect tends to oppose the magnetic change which produced it. v 4

The effect of the flux flowing through the teeth 9| and 92 then, will be to oppose relative rotation between members 89 and 93 and, as 89 is rotated at the speed of the driving shaft Hi, the member 93 together with the pilot 3| will be rotated. So long as there is slippage between members 89 and 93 there will exist an eddy-current-produced torque tending to accelerate the member 93 to the speed of member 89. When the two members are rotating in synchronism, a given point on either of members 99 and 93 will be subjected to flux of constant magnitude and no ,eddy currents will be inducedl Under this condition the holding force tending to keep the members 89 and 93 in synchronism will be entirely magnetic. It is, however, apparent that any tendency for the member 93 to slip will be instantly opposed by the eddy-current-produced torque.

In practice it will be found that the spring 25 grips the member l5 very quickly after coil 86 is energized and the magnetic effect of the flux flowing through the teeth 9|, 92 is sufficient to provide the force necessary to keep the sprin expanded. i It is believed to be apparent that the clutches illustrated in 'Figs. 6 to 10, inclusive, operate similarly to the clutch of Fig. 1, it being intended in all of the various forms of the invention to provide a ratio of approximately fifty to one between the torque transmitted by the pilot clutch structure and that transmitted through the clutch as a whole.

Any of the various modifications are adapted for automatic as well as manual operation as will be apparent to those skilled in the art.

Figs. 11 and 12 illustrate a modified form of the invention wherein reverse torque is transmitted through the pilot clutch structure. In this form of the invention, the overrunning roll ers .38 are of smaller size than those used in the above described forms and are disposed between the driven shaft H on which the cams 4|- are formed and the spring energizing lugs 29,

the spring 25 is energized by the lug 29* which is driven through the pilot 3| during clockwise rotation of the shaft l0. When shaft ||J tends to overrun shaft II, the lug 29 is rotated through the friction shoe 33; and when shaft tends to overrun shaft I0, the lug 29 and pilot member 3| are rotated through rollers 38*; thus reverse torque is transmitted from shaft II to shaft l0 through the friction shoe 33. It is of course apparent that only a small fraction of the torque capacity of the clutch can be handled by the pilot structure. However, in some installation, such as in light vehicles, the torque transmission during coasting is relatively light and is readily handled by the pilot members.

Among other advantages, this form of clutch permits complete disengagement of the drive between the two shafts. When the shaft 5| is oscillated to move the release member 46 axially of shaft [1 against spring 35, the friction shoe 33 is disengaged from the conical surface of the drivlug is in non-energizing condition.

It is of course obvious that the construction of. the Fig. 11 clutch may be readily applied to.-the' power actuatedclutches of Figs. 6-9, inclusive, to provide two-way torque transmission and to permit complete release of drive between the two shafts; consequently a detailed description is believed unnecessary.

I claim:

1. In servo-clutch mechanism for connecting driving and driven members, a driving clutch member having an internal cylindrical surface and an external conicalsurface; a driven clutch member; an expansible coil spring carried by said driven clutch member and disposed relatively to the aforesaid cylindrical surface of said driving clutch member such that it is adapted to frictionally engage the same upon expansion thereof; a pilot clutch member having a friction portion adapted to engage said conical surface of the driving clutch member; means carried by said pilot clutch member for expanding said spring in response to rotation of said pilot clutch member; and release means for disengaging said pilot clutch member from said driving structure.

2. In servo-clutch mechanism for connecting driving and driven members, a driving clutch member having an internal cylindrical surface and an external conical surface; a driven clutch member; an expansible coil spring carried by said driven clutch member and disposed relative ly to the aforesaid cylindrical surface of said driving-clutch member such that it is adapted to frictionally engage the same upon expansion thereof; a pilot clutch member having a friction portion adapted to engage said conical surface of the drivin clutch member; a'finger carried by said pilot clutch member adapted to engage one end of said spring for expanding the same in response to rotation of said pilot clutch member, and release means operably associated with said pilot clutch member for simultaneously disengaging said friction portion and said finger from driving position.

3. In servo-clutch mechanism for connecting driving and driven members, a driving member having a cylindrical surface and a conical surface; a driven member; a coil spring carried by one of the members and adapted to frictionally enga e the other member in response to application of -torque thereto; a pilot member having a friction portion adapted to engage said conical surface and a driving lug adapted to engage said spring whereby said spring is energized in response to rotation, of said pilot member.

4. The combination set forth in claim 3 wherein release means is provided for shifting said pilot member to non-driving position.

5. In servo-clutch mechanism for connecting driving and driven members, a driving structure driven by the driving member; a driven structure for driving the driven member including a torsion spring carried'by'said driven structure and disposed relatively to saiddriving structure such that it is adapted to frictionally engage the driving structure in response to torque application to said spring to connect said structuresin drive; means for applying torque to said spring comprising a pilot member adapted for releasable driving engagement with said driving structure and dynamic engagement with said spring upon engagement of said pilot member with said driving structure; and release mechanism for substantially simultaneously releasing said pilot member from-engagement with said driving structureand from dynamic engagement with said springwhereby to disconnect said driven member from drive by said driving member.

6. In a servo-clutch mechanism for connecting driving and driven members, -'a drivin clutch structure driven by the driving member, a driven clutch structure for driving the driven member, an expansible coil spring connected to said driven clutch structure and disposed relatively to the driving clutch structure such that it is adapted to frictionally engage the same upon expansion thereof, to connect'said structures in drive, a rotatable pilot clutch member adapted for releasable-driving engagement with said driving clutch structure, means operably associated with said pilot clutch member for dynamically engaging said spring in response to rotation of said pilot clutch member whereby to effect expansion of said spring, and release means for releasing said pilot member from driving engagement with said driv ing clutch structure whereby to release said spring engaging means from dynamic engagement with said spring and thereby disconnect said driven member from drive by said driving member.

7. In a servo-clutch mechanism for connecting driving and driven members, a driving clutch structure driven by the drivin member, a driven clutch structure for driving the driven member, a coil spring connected to one of said clutch structures and disposed relatively to the other clutch structure such that it is adapted to grip the same upon a change in its diameter to connect said structures in drive, a rotatable pilot member adapted for releasable driving engagement with said drivingclutch structure, said pilot member including means for dynamically engaging said spring in response to rotation of said pilot member, and there being release means for substantially simultaneously releasing said pilot member from drivin engagement with said driving structure and said "spring engaging means from dynamic engagement with said spring whereby to disconnect said driven member from drive by said driving member.

8. In a servo-clutch mechanism for connecting driving and driven members, a driving clutch structure driven by the driving member, a driven clutch structure for driving the driven member, a coil spring connected to one of said clutch structures and disposed relatively to the other clutch structure such that it is adapted to grip the same upon a change in its diameter to connect said structures in drive, a rotatable pilot member, means for establishing a releasable driving connection between said pilot member and said driv. ing clutch structure, said pilot member including means for dynamically engaging said spring in response to rotation of said ilot member; and means for controlling release of said pilot member from driving connection with said driving clutch structure whereby to release said spring engaging means from dynamic engagement with claim 8 including a reverse type overrunning con. nection operably associated with said pilot mem-- ber and driven member and arranged and constructed for preventing overrun of the driving member by the driven member under conditions when said driving and driven clutch structures are connected in drive while permitting overrun of the driving member by the driven member upon release of the driving connection between said 1 pilot member and driving clutch structure.

LUZDGER E. LA BRIE. 

